Main content

LC-MS/MS Multi Compound Analytical Method for the Determination of Pesticides and their Metabolites in Sewage Effluents and surface water

Aim

The tremendous global consumption of pesticides leads to their positive detection in natural waters. The pesticides may enter the aquatic environment via use in agriculture, during transport and on industrial premises, or on garden plots. Pesticides enter the surface water mainly due to drift and drainage from agricultural areas, or from point sources like sewage effluents. During transport (dropping) and cleaning of the spraying equipment, the pesticides may enter the sewer system. If not degraded completely, the compounds are discharged with the sewage effluents. Therefore, monitoring of the pesticide concentration in waste water is an important aspect of the surveillance of pesticide pollution. The establishment and validation of an analytical procedure for the determination of several pesticides and pesticide metabolites is described, in order to be able to monitor sewage effluent concentrations in a program in collaboration with Prof. Frede, University of Giessen, Institute of Landscape Ecology and Resources Management.

Approach

The selection of 28 pesticides and 2 major pesticide metabolites was based on annual usage in Germany, physicochemical properties and metabolism. Triazines, acetamides, organophosphates, phenoly acids and phenylurea compounds were amongst the substances selected. The diversity of the substances within the group is such that only LC-MS/MS was suitable for their selective and sensitive analytical determination. Prior to measurement the analytes were extracted from the sewage by solid phase extraction (SPE).

Results

Best results for the SPE resulted from the extraction of 0.25 l water samples at pH 4.5 with the polymeric material StrataX. Recoveries from treated sewage were mainly in the range from 80 % to 120 %, as determined using suitable internal reference compounds (Fig. 14). Limits of quantitation less than 0.05 μg/l were achieved applying the multiple reaction monitoring (MRM) mode. A total of 23 out of the 30 analyzed compounds were detected in the German sewage treatment plants investigated, 8 pesticides were quantified in the upper ng/l range and two others up to the lower μg/l level. Desamino-Metamitron, the metabolite of the herbicide metamitron was present with significantly higher concentrations than the original pesticide.

Recoveries and standard deviations [%] of the pesticides and pesticide metabolites investigated in different sewage matrices

Funding

The funded project (project 05HS022) was funded by grants from the Federal Ministry of Food, Agriculture and Consumer Protection (BMELV) given by the Federal Agency for Agriculture and Food (BLE).